Manufacture of wall board



July 2, 1935. c. o. WALPER MANUFACTURE OF' WALL BOARD Filed Aug. 5, 1953 III-4 INVENTOR.

CURRY ORA WALP ,l il u gy J ATTORNEY.

Patented July 2, 1935 "PATENT OFFICE -..-;MANUFCTURE oF WALL BOARD .',Cilrr'y'OraWalper,"Hamilton, Ontario, Canada Applicatiunnugstfs, issa-serialNo. 683,892

4 claim's. (01."154-2) {inventionrelates `to 'the manufacture fof l-wallboard f of the type Ycomprising fa v-cementitious core surrounded by paper liners and is particu- ."larly=directed to the construction of a gypsum 5 fboard havingbevelled or depressed "margins von Ladjoiningfedges of -the'boar'd' to adapt the board for-ia'dequate joint formation! during its erection `in'ibuilding construction. .1

' vThe manufacture of-A gypsum 'wallboard is :well :known yand it has Aheretofore been proposed to depresslthelongitudinal marginal edges of such boards I. w

` The-present invention will vnow bedescribed "withreference lto the accompanying drawing,` in

whichp v i i v Figure 1 is a longitudinal Aelevation of pertinent Sifeaturesof van apparatus for carrying out the linvention; 1 Y

`Figure2isa transverse-section, partially broken away, on line 2-2 of Figure 1,* f i f .Figure i3. is a transverse section, partially broken away, on line 3-3 of Figure 1;

Figure 4 is a side View of the cam shaft partially broken away;

Figure 5 is a detail view of the plate in relation to the cam; and

Figures 6 and 7 are end and longitudinal sections respectively of the board.

In the drawing, I and 2 indicate what are usually known as the squeeze rolls, which shape the core within the paper liners 3 and 4. At the upper edge of the ends of roll 2 is arranged a plate 5 which forms the depression or bevel indicated at 6 on the longitudinal margins of the board 6.

, The usual supporting belt 1 on which the board is carried is mounted on the driving rolls 8, one of which is shown in Figure 1, and the intermediate rolls I0. Y

To cause the belt to conform with the bevelled edges of the board in order that the bevelled edges may not be deformed before the core sets and the adhesive between the liner margins dries, an adjustable supporting structure for the marginal edges of the belt is provided. This structure comprises a series of relatively short rolls II, each mounted in bearings I2 movably supported on cams I3 within the guide members I4 and I5 of the frame I6, whichis provided for each roll. This structure is located at each side of the belt 1 at spaced points along the belt for a sufIicient distance to permit the board to secure an adequate set or hardening to retain its shape, before the edges of the belt are permitted to disengage the bevelled edges of vthe board. The two pair of cams I3 in the supporting structure on immediately Aopposite'sides ofthe .belt are mounted -ona shaft I1 which maybe operated by a handle ll8. Agear or sprocket wheel LIB is mounted upon one end of each of these shafts and a'belt or chain passes.overthesewheelsto move all thecams 'in unison. As .mounted in theframe, each rollis inclined Aas shown to conform with the bevel'fof the marginal edges of the board. As illustrated `in Figure 3 the rolls I I are positioned for making arelatively narrow board, say 32 inch insteadiof 48 inch. When the cams are operatedithe rolls II are. lowered so that'the'inclined marginportions of the belt vare much narrower V.and just 'sufficient .to engage the bevels on the wider board,

4the remaining portion of the belt lyinghorizontall.ly in engagement with the flat mainbodyipart Vof 'the' board.

: Towards the opposite -end roflthe conveyor-and 1in advance of. the .usual board-cutting lm'eansriis .arranged means for forminga depressionacross the moving board at successive points l.vvherethe boardisto be. out into desired lengths. Mounted across the conveyor above the roll 9 is a shaft 2l driven by a pulley 22 through a variable speed drive conventionally indicated at 23 with a speed regulator 23a, and carrying cams 24. The roll 9 is raised slightly, say one-sixteenth of an inch, above the plane of the supporting rolls and is somewhat larger in diameter in order to engage suflicient surface of the board when the latter is engaged by the plate 26 to form the desire-d depression. One of these cams located adjacent the edge of the board carries a second cam portion 25 for a purpose to be described later. A plate 26 is arranged between the cams 24 and board 6, being held in position by the spring 21. Near one of its ends the plate 26 has a slot or perforation 28 in which is mounted a springpressed plunger 29, the spring 30 normally retaining the plunger in raised position.

The operation of the process is as follows:

The slurry of hydrated calcined gypsum is fed on to the lower paper liner in advance of the squeeze rolls which form the board, the margin of the lower liner 4 being turned over to enclose the edge of the board and it is caused to adhere to the upper liner, both by the usual means, not shown in the drawing. The slight bevel 6' is formed in each edge of the board on its lower face by the plates 5. As the formed board travels forwardly the side portions of the belt yunder the bevelled edges of the board are held in a slightly raised, outwardly inclined position by the adjustable rolls II to support the bevelled edges and prevent them from sagging or becoming deformed until the board has hardened sufhciently to retain its form without such support.

It will be observed that the rolls Il are adjustable for various widths of board, so that in each case they deflect upwardly the portions of the supporting belt which are beneath the bevelled edges of the board. When the cams I3 are operated to lower the rolls Il from the position shown in Figure 3 in the manufacture of a wider board, the rolls engage the belt at points near its edge.V

After travelling beyond the zone in which the series of edge-supporting rolls Il is used, the board is given further opportunity for the core to set, as described, before it reaches the point at which it is to be severed into the desired length. Before reaching this point, the board travels under the plate 26 to form a depression across the lower face of the board. The shaft 2| reciprocating at a predetermined rate of speed causes the cams 24 to engage the'plate 2B forcing the boardagainstthe curved surface of the roll .9, thus forming a depression in the under face of the board. This depression is deepest at its central point and tapers away in both directions. A mark or slight indentation is placed on the upper face of the board at vthe central point of the depression by means of the plunger actuated by the cam portion 25. This mark or indentation on the upper surface of the board indicates the point at which the board is to be severed and the usual cutting means, not shown, is arranged to sever the board at this point. The board being moving forward when it is engaged by the plate 26, the spring 21 Als provided to return the plate to its normal position when it is released by the cams 24.

It will thus be observed that the board so formed has a bevel on its four marginal edges and on the front surface of the board which is the surface exposed when the board is erected in building construction.

It will be apparent that the usual scoring devices for the lower liner will be arranged closer' together in order to accommodate the decreased thickness of core at the edge of the board. The variable speed drive 23 will be regulated to determine the rate. of reciprocation of the cam shaft in accordance with the lengths to which the board is to be cut.

I claim:

1. In the manufacture of wallboard consisting of a gypsum core and enclosing paper liners wherein a continuous sheet of such board is formed and carried by supporting rolls', the method which comprises exerting pressure transversely of and on the upper surface of said sheet at successive spaced points along its length and against one of said supporting rolls to form depressions therein and thereafter severing said sheet at said depressions.

Y2. The method as defined in claim 1, wherein a mark is placed upon the upper surface of said sheet adjacent one edge thereof and opposite the centre line ofeach depression formed in said sheet.

3. In the manufacture of gypsum wallboard wherein a continuous sheet of board is formed on travelling supporting rolls and thereafter cut into desired lengths, the method of forming a bevel on the end margin of said board lengths which comprises automaticallyforcing a plate againstthe upper surface of the sheet at regulated intervals during the travel ofl the' sheet to force the same against a supporting roll and form a curved de'- pression in the lower face of the sheet, placing a mark on the upper face of the sheet to identify the centre of said depression and thereafter severing the sheet at each such mark.;

4. The method as defined in claim 3 wherein a bevel is placed on each longitudinalmargin of the board and supported until the board has substantially hardened.

' CURRY ORA WALPER. 

